Triglyceride

Triglycerides, or triacylglycerols, are natural fats and oils, composed of glycerin (chemically, "glycerol") and fatty acid chains. The fatty acids are linked to the glycerin so as to form 3 ester functional groups:

RCO-OCH₂-CH(O-COR')-CH₂-O-COR

where R, R', and R are long-chain alkanes (saturated fats) or alkenes (unsaturated fats). Chain lengths are in the range C₁₆ to C₂₂.

Metabolism and health

Triglycerides play an important role in metabolism as energy sources. They contain twice as much energy (8000 kcal kg^-1) as carbohydrates. In the intestine, triglycerides are split into glycerin and fatty acids (with the help of bile secretions), which can then move into blood vessels. The triglycerides are rebuilt in the blood from their fragments and can then move into cells for storage or catalysis.

In the human body, high levels of triglycerides in the bloodstream have been linked to atherosclerosis, and, by extension, to the risk of heart disease and stroke. The American Heart Association has set guidelines for triglyceride levels:

Less than 150 mg dL^-1

Normal range, lowest risk

150-199 mg dL^-1

Borderline high

200-499 mg dL^-1

High

500 mg dL^-1 and above

Very high, increased risk

Industrial uses

Triglycerides are also split into their components via transesterification during the manufacture of biodiesel. The fatty acid monoalkyl ester can be used as fuel in diesel engines. The glycerin can be used for food and in pharmaceutical production.